New Quantum Computer Algorithm Unlocks the Power of Atomic-Level Interactions

 

A revolutionary quantum computer protocol might be able to replicate the intricate dynamics of quantum materials.

A hybrid quantum-computational technique developed by RIKEN researchers is capable of quickly calculating atomic-level interactions in complicated materials. This invention makes it possible to research condensed-matter physics and quantum chemistry using conventional or smaller quantum computers, opening the door to new findings in these disciplines.

Researchers at RIKEN have created a quantum-computational algorithm that might be used to quickly and precisely analyse atomic-level interactions in complicated materials. The renowned physicist Richard Feynman initially suggested using quantum computers in condensed-matter physics and quantum chemistry in 1981, and it has the potential to provide an unprecedented level of understanding in these fields.

The promise of quantum computers includes increased computing power and the potential to solve issues that are beyond the capabilities of current computers.

The fundamental units of quantum computing, or qubits, are microscopic systems that obey the laws of quantum physics, such as nanocrystals or superconducting circuits. Qubits can simultaneously hold several values, in contrast to the one or zero bits employed in traditional computers. This characteristic of qubits is what gives quantum computers their speed advantage.

In order to solve issues that are too complex for conventional computers, an unorthodox method of computation also necessitates a novel viewpoint on how to effectively handle data.

The so-called time-evolution operator is a prominent illustration of this. Kaoru Mizuta of the RIKEN Centre for Quantum Computing notes that "Time-evolution operators are enormous grids of numbers that describe the complex behaviours of quantum materials." They are essential for better understanding quantum chemistry and the physics of solids, which gives quantum computers a very useful application.

Trotterization, a reasonably straightforward method, has been used to produce time-evolution operators in the prototype quantum computers that have been demonstrated thus far. Trotterization, however, is believed to be unsuited for the quantum computers of the future because it necessitates a substantial amount of quantum gates and thus a lengthy computation. As a result, scientists have been working to develop quantum algorithms that require fewer quantum gates to produce accurate quantum simulations.

Trotterization, a reasonably straightforward method, has been used to produce time-evolution operators in the prototype quantum computers that have been demonstrated thus far. Trotterization, however, is believed to be unsuited for the quantum computers of the future because it necessitates a substantial amount of quantum gates and thus a lengthy computation. As a result, scientists have been working to develop quantum algorithms that require fewer quantum gates to produce accurate quantum simulations.

Now, Mizuta has put out a much more effective and useful method, developed in collaboration with colleagues from across Japan. Because it is a combination of quantum and classical techniques, it may construct time-evolution operators at a lower computational cost, allowing it to be run on modest quantum computers or even conventional ones.

According to Mizuta, "We have developed a new protocol for building quantum circuits that efficiently and precisely reproduce time-evolution operators on quantum computers." Our protocol is successful in creating quantum circuits for duplicating large-scale quantum materials, but with simpler quantum computers, by fusing modest quantum algorithms with the fundamental rules of quantum dynamics.

The next step for Mizuta and his team is to explain how the time-evolution operators that have been optimised by their technique can be used with various quantum algorithms to compute the characteristics of quantum materials. We believe that this work will show how tiny quantum computers can be used to investigate physics and chemistry.

Kaoru Mizuta, Yuya O. Nakagawa, Kosuke Mitarai, and Keisuke Fujii published "Local Variational Quantum Compilation of Large-Scale Hamiltonian Dynamics" in PRX Quantum on October 5, 2022.

Reference: 10.1103/PRXQuantum.3.040302